The present invention relates generally to the design and fabrication of a composite structure comprising soft magnetic alloys and high strength fibers. More particularly, the present invention has one form defined by an internally reinforced metal matrix composite thrust disk for use in an electromagnetic thrust bearing. The selectively reinforced regions of the thrust disk contain a high strength iron cobalt metal matrix composite material. Although the present invention was developed for use in gas turbine engines, certain applications may be outside this field.
It is well known that a gas turbine engine integrates a compressor and a turbine having components that rotate at extremely high speeds in a high temperature environment. One component is a rotor disk that carries a plurality of airfoils utilized to influence the gaseous flow within the engine. The rotating components typically cooperate with a rotatable shaft and are supported by radial bearings and a thrust bearing that must withstand significant dynamic and static loads within a hostile environment. During operation of the gas turbine engine, the bearings are subjected to forces including: shock loads, such as from landings; maneuver loads, such as associated with sudden change in direction; and, centrifugal loads attendant with the mass of the rotating components.
The desire to increase efficiency and power output from gas turbine engines has caused many engine designers to consider the application of magnetic bearings for supporting the rotor and rotatable shaft. The integration of magnetic bearings into an engine will enable the rotor and rotatable shaft to be supported by magnetic forces, eliminate frictional forces, eliminate mechanical wear and allow the removal of the lubrication system.
Magnetic thrust bearings include a magnetic flux field and a rotatable thrust disk that is acted upon by the magnetic flux field. The application of magnetic thrust bearings in flight weight gas turbine engines require compactactness of bearing design, which ultimately equates to lighter weight. Prior designers of gas turbine engines have utilized materials for the rotating thrust disk that experience a loss of mechanical properties at elevated temperatures. This loss of mechanical properties limits the maximum rotational speed that the thrust disk can be operated at, thereby effectively limiting the maximum rotational speed of the engine.
Although the prior techniques utilizing magnetic thrust bearings for gas turbine engines are steps in the right direction, the need for additional improvement still remains. The present invention satisfies this need in a novel and unobvious way.